SAXA Inc. (hereinafter SAXA) is a development company of business phone systems and network equipment and has obtained significant results using the software. SAXA launched a working group specializing in thermal design, and then in-house rules were prepared for selecting and utilizing software product before adopting HeatDesigner. 'HeatDesigner' is developed by Software Cradle and is one of the major thermo-fluid analysis software for electronic devices. And the company has achieved zero production rework in only one year. This time, we interviewed a SAXA staff about how they made full use of the software and what lies behind their success.